We determined the appropriate sample size for each group before starting the study by power calculations using SPSS Sample Power (IBM, Tokyo, Japan) and assumed that the maximal reduction in arterial stiffness after intervention would be 4–7 % according to the previous results (Nishiwaki et al. 2014b (link); Yamamoto et al. 2009 (link)). To detect this difference at 80 % power and with a two-tailed α of 5 %, the intervention group should comprise eight participants. Thus, we recruited 16 participants and assigned them to control and intervention groups (n = 8 per group).
Both groups were assessed before and after the experimental period. All tests and interventions proceeded in a quiet air-conditioned room (22–24 °C) at the same time of day and at the same number of hours after the last meal to avoid potential diurnal variations. The participants were required to abstain from caffeine and fast for ≥4 h before each test and then were assessed at least 24 h after the most recent stretching session to avoid any acute effects.
Both groups were assessed before and after the experimental period. All tests and interventions proceeded in a quiet air-conditioned room (22–24 °C) at the same time of day and at the same number of hours after the last meal to avoid potential diurnal variations. The participants were required to abstain from caffeine and fast for ≥4 h before each test and then were assessed at least 24 h after the most recent stretching session to avoid any acute effects.
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